NASA Cassini Significant Events for 08/27/08 - 09/02/08

The most recent spacecraft telemetry was acquired on Sept. 2 from the Deep Space Network tracking complex at Madrid, Spain. The Cassini spacecraft is in an excellent state of health and all subsystems are operating normally.

An AACS piggyback gyro calibration was completed today. The term "piggyback" is applied when the calibration is combined with an activity that already turns the spacecraft. Sometimes a separate calibration activity is scheduled with independent turns specifically for that activity.

The kick-off meeting for the S48 Science Operations Plan implementation process was held today. The process will run for about twelve more weeks and conclude on Nov. 21. At that time the final sequence development process will begin. S48 begins execution on board the spacecraft in February of 2009.

Using the latest Navigation orbit determination solution for the result of maneuver 164, analysis has been performed on a proposed live update due to execute on DOY-254. Both the prime instrument for this time frame, the Ultraviolet Imaging Spectrograph (UVIS), and Science Planning have recommended a "no go" so the update has been cancelled.

A combined Optical Remote Sensing (ORS) campaign to look for auroras in Saturn's south polar region filled up eleven and a half hours of observation time today. The day concluded with an Optical Navigation (OPNAV) image. OPNAVs are images taken by the narrow-angle camera of one of Saturn's moons against a star background. Analysis of these images allows the Navigation team to make more accurate estimates of the orbital paths of both the moons and the spacecraft.

Thursday, Aug. 28 (DOY 241):

Science today began with a nearly nine-hour Composite Infrared Spectrometer (CIRS) observation of Saturn's rings. This was followed with a five-hour joint ORS observation of Saturn's moon Rhea. Rhea appears as a thin crescent, which provides the ORS instruments views of unique shadows as well as the "night side" of the moon.

Saturday, Aug. 30 (DOY 243):

The Cassini Plasma Spectrometer (CAPS), which is one of the four Magnetospheric and Plasma Science (MAPS) instruments, took control of the spacecraft to point its sensors toward the magnetic field of Saturn. This was followed by an ISS on-going campaign to further deduce the orbits of some of the lesser-known satellites of Saturn. Science activities concluded with a thirteen hour "movie" of Saturn's F ring by three instruments: Visual and Infrared Mapping Spectrometer (VIMS), CIRS, and ISS.

Sunday, Aug. 31 (DOY 244):

A non-targeted flyby of Titan occurred today.

Titan composition observations performed by CIRS began today's science activities. This was a seven-hour long series of infrared images of Titan's mid-southern latitudes. ISS and CIRS then continued their long-term temporal monitoring of the F ring.

Monday, Sept. 1 (DOY 245):

Solar conjunction occurs during the week of Sept. 1 as the Sun-Earth-Probe (SEP) angle drops below 3 degrees. Approximately once a year the orbital motions of Earth and Saturn create an alignment where the sun blocks the view of Earth as seen from Saturn and the Cassini spacecraft. In preparation for this, the command loss timer was set to 10 days from the normal 90 hours on Aug. 30. It will be decremented daily during the conjunction period until Sept. 7, when it will be returned to the normal value. Spacecraft operating rules during this period fix spacecraft pointing to Earth. With this, the MAPS and Radio Science instruments will be the only ones performing science observations during the conjunction period. This particular orientation is generally not usable by the other instruments.

Tuesday, Sept. 2 (DOY 246):

A non-targeted flyby of Janus occurred today.

On this the second day of solar conjunction, the spacecraft continued to be Earth-pointed with science activities restricted to Magetospheric and Plasma Science (MAPS) and Radio Science observations. Later today, the SEP angle will drop to 2 degrees. Minimum separation will occur tomorrow at 1.67 degrees.